US8944641B2 - Lighting device, display device and television receiver - Google Patents

Lighting device, display device and television receiver Download PDF

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Publication number
US8944641B2
US8944641B2 US13/512,709 US201013512709A US8944641B2 US 8944641 B2 US8944641 B2 US 8944641B2 US 201013512709 A US201013512709 A US 201013512709A US 8944641 B2 US8944641 B2 US 8944641B2
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raised
light
raised portions
portions
lighting device
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US20120236204A1 (en
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Nobuhiro Kasai
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Sharp Corp
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Sharp Corp
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    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G02F1/133602—Direct backlight
    • G02F1/133603—Direct backlight with LEDs
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G02F1/133602—Direct backlight
    • G02F1/133604—Direct backlight with lamps
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G02F1/133602—Direct backlight
    • G02F1/133605—Direct backlight including specially adapted reflectors
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G02F1/133602—Direct backlight
    • G02F1/133606—Direct backlight including a specially adapted diffusing, scattering or light controlling members
    • G02F1/133607—Direct backlight including a specially adapted diffusing, scattering or light controlling members the light controlling member including light directing or refracting elements, e.g. prisms or lenses
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G02F1/133602—Direct backlight
    • G02F1/133608—Direct backlight including particular frames or supporting means
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G02F1/133602—Direct backlight
    • G02F1/133611—Direct backlight including means for improving the brightness uniformity
    • G02F2001/133607—

Definitions

  • the present invention relates to a lighting device, a display device, and a television receiver.
  • a liquid crystal panel for a liquid crystal display device such as a liquid crystal television does not emit light, and thus a backlight unit is required as a separate lighting device.
  • the backlight unit that is provided at a rear side (side opposite to a display surface) of the liquid crystal panel includes: a chassis that is open on a side close to the liquid crystal panel; a light source housed in the chassis; a reflection sheet provided along an inner surface of the chassis and configured to reflect light toward the opening of the chassis; and an optical member (such as a diffuser sheet) provided at the opening of the chassis and configured to efficiently direct the light emitted from the light source to the liquid crystal panel.
  • LEDs may be used as the light source.
  • a great number of LEDs is arranged, for instance, on a bottom plate of the chassis in a planar arrangement.
  • dark regions due to shortage of light amount may be observed at four corners of the screen.
  • Patent Document 1 discloses that the number of LEDs arranged on the bottom plate of the chassis in a planar arrangement is greater in the vicinity of the corners than in the middle portion. With such an arrangement, an increased number of LEDs emit light in the vicinity of the corners, and thus the shortage of the light amount at the corners is accordingly compensated.
  • Patent Document 1 results in an increase in the entire number of the LEDs used in the backlight unit, and thus the manufacturing cost thereof will be increased in accordance with the increase in the number of the LEDs. Further, in order to change the number of the LEDs depending on the positions of the LEDs in the chassis, LEDs are required to be arranged on an LED board in a disproportional manner, which requires a dedicated LED board. Accordingly, general-purpose LED boards on which the LEDs are equidistantly aligned are not usable, which will result in a further increase of the manufacturing cost.
  • the present invention was made in view of the foregoing circumstances and an objective of the present invention is to restrict uneven brightness at low cost.
  • a lighting device includes: a light source; a chassis including a bottom plate provided on a side opposite to a light exit side with respect to the light source, the chassis housing the light source; and a reflection member configured to reflect light and including a quadrangular bottom portion and at least two raised portions.
  • the bottom portion is arranged along the bottom plate and each of the at least two raised portions is raised from at least adjacent two sides of the bottom portion toward the light exit side, and each raised portion has a side edge and the tow raised portions form a joint between adjacent two side edges of the raised portions.
  • the at least two raised portions includes a one raised portion and another raised portion, and the one raised portion includes a facing portion on the side edge thereof so as to face the side edge of the other raised portion with respect to a direction directing from the bottom toward the one raised portion, and the one raised portion and the facing portion bulge toward the light output side.
  • the joint is provided between the adjacent side edges of the at least two raised portions raised toward the light exit side from the at least adjacent two sides of the quadrangular bottom. If the raised portions are warped and deformed in a direction opposite to the light exit side, a gap may be generated at the joint. The light may accordingly leak out through the gap, and thus a dark region may be locally generated.
  • One of the solutions to such a problem is, for instance, to increase the number of LEDs in the vicinity of the joint. However, the increase in the number of LEDs leads to a cost increase.
  • the side edge of the one raised portion of the at least two raised portions is provided with the facing portion that faces the side edge of the other raised portion in the direction where the one raised portion is raised from the bottom, and the one raised portion and the facing portion bulge toward the light exit side. Therefore, the side edge of the other raised portion receives a stress that biases the other raised portion toward the light exit side from the facing portion that is provided to face the other raised portion.
  • the stress applied from the facing portion restricts the other raised portion from being deformed in the direction opposite to the light exit side, and the other raised portion is less likely to be deformed. Accordingly, a gap is not generated at the joint between the side edge of the one raised portion and the side edge of the other raised portion. Thus, without increasing the number of the light source, the light is prevented from leaking out through the joint, and uneven brightness is suppressed at low cost.
  • a display device includes: the above-described lighting device; and a display panel adapted to display with use of light from the lighting device.
  • the lighting device supplying the light to the display panel suppresses uneven brightness at low cost, and this achieves excellent display quality at low cost.
  • a liquid crystal panel may be used as the display panel may.
  • the above-configured display device is applicable as a liquid crystal display device to several uses such as uses in display devices of television sets or personal computers. Specifically, the above-configured display device is more favorably applicable to uses in large-screen display devices.
  • uneven brightness is restricted at low cost.
  • FIG. 1 is an exploded perspective view schematically depicting a television receiver of a first exemplary embodiment according to an aspect of the present invention
  • FIG. 2 is an exploded perspective view schematically depicting a liquid crystal display device included in the television receiver
  • FIG. 3 is a top view depicting a layout of LED boards, a first reflection sheet and holding members in a chassis of the liquid crystal display device;
  • FIG. 4 depicts a cross section of the liquid crystal display device in FIG. 3 taken along the segment iv to iv;
  • FIG. 5 depicts a cross section of the liquid crystal display device in FIG. 3 taken along the segment v to v;
  • FIG. 6 is a top view depicting a detailed layout of the LED boards and the holding members
  • FIG. 7 depicts a cross section of FIG. 6 taken along the segment vii to vii;
  • FIG. 8 depicts a cross section of FIG. 6 taken along the segment viii to viii;
  • FIG. 9 is an enlarged top view depicting a corner of the chassis when the bent first reflection sheet is mounted on the chassis and a diffuser plate is attached;
  • FIG. 10 depicts a top cross section of FIG. 9 ;
  • FIG. 11 depicts a cross section of FIG. 9 taken along the segment xi to xi;
  • FIG. 12 depicts a cross section of FIG. 9 taken along the segment xii to xii;
  • FIG. 13 is a top view depicting the spread first reflection sheet
  • FIG. 14 depicts a cross section of FIG. 13 taken along the segment xiv to xiv;
  • FIG. 15 depicts a cross section of FIG. 13 taken along the segment xv to xv;
  • FIG. 16 is an enlarged top view depicting a corner of the chassis when the bent first reflection sheet is mounted on the chassis but before the diffuser plate is attached;
  • FIG. 17 depicts a top cross section of FIG. 16 ;
  • FIG. 18 depicts a cross section of FIG. 13 taken along the segment xviii to xviii;
  • FIG. 19 depicts a cross section of FIG. 13 taken along the segment xix to xix;
  • FIG. 20 is a top cross sectional view depicting a second raised portion when the first reflection sheet is thermally expanded
  • FIG. 21 is a top view depicting a layout of a hot cathode tube and a reflection sheet in a chassis of a second exemplary embodiment according to an aspect of the present invention
  • FIG. 22 depicts a cross section of FIG. 21 taken along the segment xxii to xxii;
  • FIG. 23 is a top view for explaining a distribution of light reflectance in a diffuser plate
  • FIG. 24 is an enlarged top view primarily and schematically depicting a surface of the diffuser plate opposed to the hot cathode tube;
  • FIG. 25 depicts a graph for indicating changes of light reflectance in a short-side direction of the diffuser plate
  • FIG. 26 is a top view depicting a layout of a cold cathode tube and a reflection sheet in a chassis of a third exemplary embodiment according to the aspect of the present invention.
  • FIG. 27 is a top cross sectional view depicting a relationship between a first raised portion, second raised portion and counter portion of another first exemplary embodiment according to the aspect of the present invention.
  • FIG. 28 depicts a cross section of a first raised portion and an extension of a spread first reflection sheet of another second exemplary embodiment according to the aspect of the present invention.
  • FIG. 29 depicts a cross section of a second raised portion and an extension of a spread first reflection sheet.
  • FIGS. 1 to 20 A first exemplary embodiment according to an aspect of the present invention will be described with reference to FIGS. 1 to 20 .
  • a liquid crystal display device 10 will be exemplarily described.
  • Parts of the attached drawings indicate an X-axis, Y-axis and Z-axis, in which each axial direction coincides with the direction indicated in the drawings.
  • the upper sides in FIGS. 3 and 4 will be a front side while the lower sides therein will be a rear side.
  • a television receiver TV includes: the liquid crystal display device 10 ; front and rear cabinets Ca and Cb that sandwich the liquid crystal display device 10 to house the liquid crystal display device 10 therein; a power source P; a tuner T; and a stand S.
  • the liquid crystal display device (display device) 10 which is in whole transversely (elongated) quadrangular (rectangular), is housed in a vertically standing posture.
  • the liquid crystal display device 10 includes: a liquid crystal panel 11 serving as a display panel; and a backlight unit (lighting device) 12 serving as an external light source.
  • a bezel 13 shaped like a frame, and other components hold and integrate the liquid crystal panel 11 and the backlight unit 12 together.
  • the liquid crystal panel 11 which is transversely quadrangular in a planar view, is configured such that a pair of glass substrates is joined together with a predetermined gap interposed therebetween and liquid crystal is enclosed in between the glass substrates.
  • a first glass substrate is provided with: a switching component (e.g., TFT) connected to a source wiring and a gate wiring orthogonal to each other; a pixel electrode connected to the switching component; and further an alignment film and the like.
  • a switching component e.g., TFT
  • a second glass substrate is provided with: a color filter in which color sections such as R (red), G (green) and B (blue) sections are disposed in a predetermined alignment; counter electrodes; and further an alignment film and the like.
  • a polarizing plate is provided outside of the two glass substrates.
  • the backlight unit 12 includes: a substantially box-shaped chassis 14 having an opening 14 b at a light exiting side (side of liquid crystal panel 11 ); a group of an optical member 15 (a diffuser plate (light diffuser member) 15 a and a plurality of optical sheets 15 b provided between the diffuser plate 15 a and the liquid crystal panel 11 ) provided to cover the opening 14 b of the chassis 14 ; and a frame 16 disposed to follow an outer periphery of the chassis 14 and hold an outer periphery of the group of the optical member 15 by sandwiching with the chassis 14 the outer periphery of the group of the optical member 15 .
  • a substantially box-shaped chassis 14 having an opening 14 b at a light exiting side (side of liquid crystal panel 11 ); a group of an optical member 15 (a diffuser plate (light diffuser member) 15 a and a plurality of optical sheets 15 b provided between the diffuser plate 15 a and the liquid crystal panel 11 ) provided to cover the opening 14 b of the chassis 14
  • interior of the chassis 14 includes: an LED (light emitting diodes) 17 serving as a light source; an LED board 18 mounted with the LED 17 ; and a diffusing lens 19 attached to the LED board 18 at a position corresponding to the LED 17 .
  • the interior of the chassis 14 further includes: a holding member 20 adapted to hold with the chassis 14 the LED board 18 ; and a reflection sheet 21 that reflects the light in the chassis 14 to the optical member 15 .
  • a side closer to the optical member 15 relative to the LED 17 serves as the light exiting side. In the following description, components of the backlight unit 12 will be described in detail.
  • the chassis 14 which is exemplarily made of metal, includes: a bottom plate 14 a that is transversely quadrangular (rectangular) similarly to the liquid crystal panel 11 ; a lateral plate 14 c that stands from outer ends of sides (a pair of long sides and a pair of short sides) of the bottom plate 14 a toward the front side (light exiting side); and a receiving plate 14 d that extends outward from a standing end of the lateral plate 14 c .
  • the chassis 14 has a substantially shallow box shape (substantially shallow dish shape) that is opened toward the front side.
  • the long sides of the chassis 14 extend in the same direction as the X-axis direction (transverse direction) while the short sides thereof extend in the same direction as the Y-axis direction (vertical direction).
  • the receiving plate 14 d of the chassis 14 is adapted to be mounted with the frame 16 and the optical member 15 (described below) from the front side.
  • the frame 16 is mounted to the receiving plate 14 d with screws.
  • the bottom plate 14 a of the chassis 14 is provided with an attachment hole 14 e adapted to be attached with the holding member 20 .
  • the attachment hole 14 e is configured such that a plurality of attachment holes 14 e is provided to the bottom plate 14 a respectively at positions corresponding to attachment positions of the holding members 20 .
  • the optical member 15 is also transversely quadrangular (rectangular) in a planar view, like the liquid crystal panel 11 and the chassis 14 .
  • the optical member 15 covers the opening 14 b of the chassis 14 while being interposed between the liquid crystal panel 11 and the LED 17 .
  • the optical member 15 includes: the diffuser plate 15 a positioned at the rear side (side of the LED 17 , i.e., opposite to the light exiting side); and the optical sheets 15 b positioned at the front side (side of the liquid crystal panel 11 , i.e., the light exiting side).
  • the diffuser plate 15 a which is configured such that a number of diffusing particles is dispersed in a substantially transparent resin base substrate having a predetermined thickness, is adapted to diffuse the light transmitted through the diffuser plate 15 a .
  • the optical sheets 15 b are sheets having smaller thickness than the diffuser plate 15 a . In FIGS. 7 and 8 , two optical sheets 15 b are layered. Examples of the optical sheets 15 b are diffuser sheets, lens sheets and reflection type polarizing sheets. In use, the optical sheets 15 b may be selected from the above examples as needed.
  • the frame 16 is a frame that conforms to outer circumferences of the liquid crystal panel 11 and the optical member 15 .
  • the frame 16 is adapted to sandwich with the receiving plate 14 d the outer periphery of the optical member 15 (see, FIGS. 4 and 5 ).
  • the frame 16 is also adapted to be mounted with an outer periphery of the liquid crystal panel 11 from the rear side, such that the outer periphery of the liquid crystal panel 11 is sandwiched between the frame 16 and the bezel 13 mounted to the liquid crystal panel 11 from the front side (see, FIGS. 4 and 5 ).
  • the LED 17 and the LED board 18 mounted with the LED 17 will be described.
  • the LED 17 is structured such that a LED chip is, with a resin material, sealed onto a substrate fixed to the LED board 18 .
  • the LED chip mounted on the substrate emits light of one main emission wavelength. Specifically, an LED chip that emits monochromatic light of blue color is in use.
  • the resin material adapted to seal the LED chip is blended with fluorescent substance such that the fluorescent substance is dispersed in the resin material.
  • the fluorescent substance converts the blue light emitted by the LED chip into white light.
  • the LED 17 is configured to emit white light.
  • the LED 17 is a so-called top-emitting device whose emitting surface is opposite to the surface mounted to the LED board 18 (the emitting surface facing the optical member 15 ).
  • the LED board 18 has a base substrate transversely quadrangular in a planar view.
  • the long sides of the LED board 18 extend in the same direction as the X-axis direction while the short sides thereof extend in the same direction as the Y-axis direction.
  • the LED board 18 is housed in the chassis 14 to extend along the bottom plate 14 a .
  • the base member of the LED board 18 is, like the chassis 14 , made of metal such as an aluminum-based material.
  • a front surface of the LED board 18 is provided with a wiring pattern made of metal film such as copper foil with an interposition of an insulating layer.
  • the base member of the LED board 18 may be made of an insulating material such as ceramic.
  • a front surface (the surface facing the optical member 15 ) of the base member of the LED board 18 is surface-mounted with the LED 17 configured as above.
  • the LED 17 is configured such that a plurality of LEDs 17 is juxtaposed linearly along the long-side direction (X-axis direction) of the LED board 18 , and connected serially with one another by the wiring pattern of the LED board 18 .
  • Arrangement pitches of the LEDs 17 are substantially constant. In other words, the LEDs 17 are equidistantly arranged.
  • both longitudinal ends of the LED board 18 are provided with connectors 18 a.
  • the above-described LED board 18 is configured such that a plurality of LED boards 18 is juxtaposed both in the X-axis and Y-axis directions within the chassis 14 , with their long and short sides aligned respectively in the same directions.
  • the LED boards 18 and the LEDs 17 mounted thereon are both disposed in the chassis 14 to form a matrix (disposed in a plane arrangement), in which the X-axis direction (direction along the long sides of the chassis 14 and the LED boards 18 ) is coincident with the row direction of the matrix while the Y-axis direction (direction along the short sides of the chassis 14 and the LED boards 18 ) is coincident with the column direction of the matrix.
  • the chassis 14 three LED boards 18 in the X-axis direction and nine LED boards 18 in the Y-axis direction are aligned in juxtaposition, whereby twenty seven LED boards 18 in total are aligned in juxtaposition therein.
  • the LED boards 18 that are juxtaposed in the X-axis direction to forma row are electrically connected with one another by fittably connecting adjacent pairs of connectors 18 a .
  • the connectors 18 a positioned to correspond to both X-axial ends of the chassis 14 are electrically connected to an outer control circuit (not depicted).
  • the LEDs 17 disposed on the single-row forming LED boards 18 are serially connected with one another, and the great number of LEDs 17 included in the single row is, with use of a single control circuit, controllably switched on and off in a lump sum manner.
  • the arrangement pitches of the LED boards 18 aligned in the Y-axis direction are substantially equal.
  • the LEDs 14 disposed in a plane arrangement along the bottom plate 14 a in the chassis 14 are substantially equidistantly juxtaposed both in the X-axis direction and the Y-axis direction.
  • the diffusing lens 19 is made of a substantially transparent (capable of high light transmission) synthetic resin material having a higher refraction index than air (such as polycarbonate or acrylic). As depicted in FIGS. 6 to 8 , the diffusing lens 19 , which has a predetermined thickness, is substantially circular in a planar view.
  • the diffusing lens 19 is attached to the LED board 18 to cover the LED 17 discretely from the front side (i.e., be superposed over the LED in a planar view).
  • the diffusing lens 19 is adapted to diffuse highly directional light emitted by the LED 17 and let out the light. In other words, the light emitted by the LED 17 reduces its directionality while passing through the diffusing lens 19 .
  • the diffusing lens 19 is positioned substantially concentrically with the LED 17 in a planar view.
  • a surface facing rearward to oppose to the LED board 18 provides a light incident surface 19 a through which the light from the LED 17 is incident, while a surface facing frontward to oppose to the optical member 15 provides a light exiting surface 19 b through which the light is let out.
  • the light incident surface 19 a in a whole, follows the plate surface of the LED board 18 (in X-axis and Y-axis directions).
  • a light-incident recess 19 c provided to the light incident surface 19 a at a position to be superposed over the LED 17 in a planar view provides a tilted surface tilted with respect to the optic axis LA of the LED 17 .
  • the light-incident recess 19 c is substantially conical with an inverted-V shaped cross section, and positioned substantially concentrically with the diffusing lens 19 .
  • the light emitted from the LED 17 and entering the light-incident recess 19 c is refracted by the tilted surface at a wide angle to be incident on the diffusing lens 19 .
  • an attachment leg 19 d adapted to be attached to the LED board 18 protrudes from the light incident surface 19 a .
  • the light exiting surface 19 b which is substantially flatly spherical, is adapted to refract at a wide angle the light let out from the diffusing lens 19 , and let out the light therethrough.
  • the light exiting surface 19 b has substantially bowl-shaped light exiting recess 19 e at a position to be superposed over the LED 17 in a planar view. With the light exiting recess 19 e , much of the light from the LED 17 is configured to be refracted and let out at a wide angle, or the light from the LED 17 is partially reflected to the LED board 18 .
  • the holding member 20 is made of synthetic resin such as polycarbonate, and a surface thereof is white, which is excellent in terms of light reflectance.
  • the holding member 20 includes: a body 20 a that follows the plate surface of the LED board 18 ; and a fixed portion 20 b that protrudes from the body 20 a to the rear side (i.e., to the chassis 14 ) to be fixed to the chassis 14 .
  • the body 20 a having a substantially circular plate shape in a planar view, is adapted to sandwich with the bottom plate 14 a of the chassis 14 the LED board 18 and the later-described reflection sheet 21 .
  • the fixed portion 20 b is to be locked with the bottom plate 14 a of the chassis 14 by penetrating through an insertion hole 18 b and the attachment hole 14 e .
  • the through insertion hole 18 b and the attachment hole 14 e are respectively provided to the LED board 18 and the bottom plate 14 a at positions corresponding to the attachment positions of the holding member 20 .
  • the holding member 20 is configured such that a great number of holding members 20 is juxtaposed within the planes of the LED boards 18 to form a matrix.
  • the holding members 20 are positioned between pairs of diffusing lenses 19 (LEDs 17 ) that are adjacent to each other in the X-axis direction.
  • a pair of holding members 20 positioned near the middle of the screen is provided with supports 20 c that protrude from bodies 20 a toward the front side to support the diffuser plate 15 a from the rear side by the supports 20 c .
  • the LEDs 17 and the optical member 15 are configured to keep constant their positional relationship in respect of the Z-axis direction, and thus an inadvertent deformation of the optical member 15 is prevented.
  • the reflection sheet 21 includes: a first reflection sheet 22 sized to cover substantially the entirety of the inner surface of the chassis 14 ; and a second reflection sheet 23 sized to cover LED board 18 discretely.
  • the reflection sheets 22 and 23 are both made of synthetic resin, and surfaces thereof are white, which is excellent in terms of light reflectance.
  • the reflection sheets 22 and 23 are both adapted to extend along the bottom plate 14 a (LED boards 18 ) within the chassis 14 .
  • the second reflection sheet 23 will be described. As depicted in FIGS. 6 to 8 , the second reflection sheet 23 , like the LED boards 18 to which the second reflection sheet 23 is applied, is transversely quadrangular in a planar view, and adapted to cover substantially the entirety of the LED boards 18 from the front side. The second reflection sheet 23 is superposed over the front surfaces of the LED boards 18 , and thus positioned to face the diffusing lenses 19 . In other words, the second reflection sheet 23 is interposed between the diffusing lenses 19 and the LED boards 18 .
  • the second reflection sheet 23 serves to re-reflect to the diffusing lenses 19 light returned from the diffusing lenses 19 to the LED boards 18 , and also light incident from the outside of the diffusing lenses 19 into the gap between the diffusing lenses 19 and the LED boards 18 in a planar view.
  • short sides of the second reflection sheet 23 are sized to be larger than those of the LED boards 18 and diameters of the diffusing lenses 19 and lens insertion holes 22 a of the later-described first reflection sheet 22 . Accordingly, peripheries of the lens insertion holes 22 a are positioned on a front surface of the second reflection sheet 23 by layering the first reflection sheet 22 on the front surface of the second reflection sheet 23 . With this arrangement, the first reflection sheet 22 and the second reflection sheet 23 seamlessly and continuously extend in the chassis 14 in a planar view, and the chassis 14 or the LED boards 18 are hardly exposed to the front side through the lens insertion holes 22 a .
  • the second reflection sheet 23 has: LED insertion holes 23 a through which the LEDs 17 penetrate; leg insertion holes 23 b through which the attachment legs 19 d of the diffusing lenses 19 penetrate; and insertion holes 23 c through which the fixed portions 20 b of the holding members 20 penetrate.
  • the LED insertion holes 23 a , the leg insertion holes 23 b and the insertion holes 23 c are bored in the second reflection sheet 23 at positions respectively to be superposed over the LEDs 17 , the attachment legs 19 d and the fixed portions 20 b in a planar view.
  • the bottom 24 is transversely (elongated) quadrangular (rectangular), like the bottom plate 14 a of the chassis 14 . Long sides of the bottom 24 extend in the same direction as the X-axis direction while short sides thereof extend in the same direction as the Y-axis direction.
  • the bottom 24 has the lens insertion holes 22 a through which not only the LEDs 17 disposed in the chassis 14 but also the diffusing lenses 19 covering the LEDs 17 are inserted.
  • the plurality of lens insertion holes 22 a is provided in juxtaposition at positions to be superposed over the LEDs 17 and the diffusing lenses 19 in a planar view, thereby forming a matrix.
  • the lens insertion holes 22 a are circular in a planar view, and their diameters are sized to be larger than the diameters of the diffusing lenses 19 .
  • the diffusing lenses 19 may reliably penetrate through the lens insertion holes 22 a , irrespective of dimension errors.
  • the first reflection sheet 22 covers regions interposed between adjacent pairs of diffusing lenses 19 and outer circumferential regions of the diffusing lenses 19 in the chassis 14 .
  • the first reflection sheet 22 serves to reflect light directed to these regions toward the optical member 15 .
  • the bottom 24 of the first reflection sheet 22 has insertion holes 22 b through which the fixed portion 20 b of the holding members 20 penetrate.
  • the insertion holes 22 b are bored in the bottom 24 at positions to be superposed over the fixed portions 20 b in a planar view.
  • first raised portions (one raised portion) 25 are raised from the pair of long sides of the bottom 24 of the first reflection sheet 22 toward the front side (i.e., the light exit side), while second raised portions (another raised portion) 26 are raised from the pair of short sides thereof toward the front side (i.e., the light exit side).
  • the first raised portions 25 protrude outward in the Y-axis direction from the long sides of the bottom 24 in a planar view.
  • the pair of first raised portions 25 is positioned to interpose the bottom 24 therebetween in respect of the Y-axis direction.
  • the second raised portions 26 protrude outward in the X-axis direction from the short sides of the bottom 24 in a planar view.
  • the pair of second raised portions 26 is positioned to interpose the bottom 24 therebetween in respect of the X-axis direction.
  • the long sides of the bottom 24 are adjacent to the pair of short sides, while the short sides thereof are adjacent to the pair of long sides.
  • the first raised portions 25 raised from the long sides of the bottom 24 are adjacent to the pair of second raised portions 26
  • the second raised portions 26 raised from the short sides of the bottom 24 are adjacent to the pair of the first raised portions 25 .
  • a direction in which the first raised portions 25 are raised from the bottom 24 coincides with the Y-axis direction.
  • a direction in which the second raised portions 26 are raised from the bottom 24 coincides with the X-axis direction.
  • both of the first and second raised portions 25 and 26 extend outward from the center (inside) of the first reflection sheet 22 .
  • raised distal ends of the raised portions 25 and 26 are provided with extensions 27 that extend outward.
  • the extensions 27 are mounted to the receiving plate 14 d of the chassis 14 , and sandwiched between the receiving plate 14 d and the diffuser plate 15 a.
  • the first raised portions 25 and the second raised portions 26 are substantially linearly tapered from the bottom 24 at a predetermined raising angle.
  • the first reflection sheet 22 is, in its entirety, substantially bowl shaped.
  • the raising angles at which the pair of first raised portions 25 is raised from the bottom 24 i.e., the angles formed by the pair of first raised portions 25 with respect to the bottom 24
  • the raising angles at which the pair of second raised portions 26 is raised from the bottom 24 i.e., the angles formed by the pair of second raised portions 26 with respect to the bottom 24
  • the angles given to the reflection light by the first raised portions 25 become substantially equal while the angles given to the reflection light by the second raised portions 26 also become substantially equal, which favorably restricts uneven brightness.
  • the raised portions 25 and 26 , and the lateral plate 14 c and the bottom plate 14 a of the chassis 14 define a substantially triangular space S in a side view, the oblique line of which coincides with the tapering of the tapered raised portions 25 and 26 (see, FIGS. 4 and 5 ).
  • the first reflection sheet 22 is shaped as above by bending at predetermined positions a spread sheet punched out from a large-sized base material (not depicted) during the manufacturing process. As depicted in FIG. 13 , while the first reflection sheet 22 remains to be a spread sheet, the first raised portions 25 and the second raised portions 26 are substantially trapezoidal in a planar view.
  • the upper bases (shorter sides) thereof are positioned inward, and each side of the bottom 24 is continued from the upper bases, while the lower bases (longer sides) are positioned outward, and the extensions 27 are continued from the lower bases.
  • the side edges 25 a and 26 a of the first raised portions 25 and the second raised portions 26 respectively are inclined with respect to both of the X-axis and Y-axis directions in a planar view.
  • a predetermined clearance is provided between the side edges 25 a and 26 a of the neighboring first raised portions 25 and the second raised portions 26 respectively.
  • the clearance is increased gradually from a raised base end (inner side) toward a raised distal end (outer side), to be substantially triangular in a planar view.
  • the first raised portions 25 are symmetrical with respect to a segment passing through their centers in the Y-axis direction while the second raised portions 26 are symmetrical with respect to a segment passing through theirs center in the X-axis direction.
  • the first reflection sheet 22 is a large-sized and highly thermally expandable component made of synthetic resin.
  • the first reflection sheet 22 tends to be expanded or contracted in a great amount due to thermal expansion or contraction.
  • the bottom 24 of the first reflection sheet 22 is expanded or contracted in a direction along its long sides (the X-axis direction) in a greater amount than in a direction along its short sides (the Y-axis direction) due to thermal expansion or contraction.
  • positions of the raised base ends of the second raised portions 26 at which the second raised portions 26 are raised from the short sides of the bottom 24 , are comparatively more greatly displaced than those of the first raised portions 25 raised from the long sides thereof.
  • positions of the raised distal ends of the second raised portions 26 are substantially fixed, with the extensions 27 continued therefrom sandwiched between the receiving plate 14 d and the diffuser plate 15 a . Therefore, when the first reflection sheet 22 is thermally expanded, the positions of the raised base ends of the second raised portions 26 can be greatly displaced outward in the X-axis direction to come toward the raised distal ends, and in accordance therewith, the distance between the positions of the raised base ends and the positions of the raised distal ends will be greatly reduced, thereby generating a great deflection.
  • the raised base ends of the second raised portions 26 can be displaced as if pulled toward the rear side (opposite to the light exiting side), and the second raised portions 26 can be deformed.
  • the side edges 26 a thereof are displaced to be away from the side edges 25 a of the first raised portions 25 , which brings a clearance to the joints J.
  • the clearance is brought to the joints J, the light is not reflected at the position of the clearance, and is leaked out of the first reflection sheet 22 . Therefore, in the light exiting surface of the entire backlight unit 12 , dark regions can be generated locally at the four corners thereof where the joints J are positioned, thereby causing uneven brightness.
  • the first reflection sheet 22 is configured such that the side edges 25 a of the long sides of the first raised portions 25 are provided with facing portions 28 as depicted in FIGS. 9 and 10 .
  • the facing portions 28 extend outward in the Y-axis direction relative to the side edges 26 a of the second raised portions 26 ; in other words, the facing portions 28 face the side edges 26 a by extending in the direction where the first raised portions 25 are raised from the bottom 24 .
  • the first raised portions 25 provided with the facing portions 28 together with the facing portions 28 , bulge toward the front side (i.e., the light exiting side).
  • first raised portions 25 and the facing portions 28 in aside view, gradually bulge toward the front side as from the raised base ends and raised distal ends to the middle side, thereby forming an arched shape.
  • the first raised portions 25 and the facing portions 28 bulge the most at the middle position in the raised direction.
  • Inner surfaces of the facing portions 28 (surfaces facing the second raised portions 26 ) abut on end faces of the side edges 26 a of the adjacent second raised portions 26 , thereby applying to the side edges 26 a a stress that biases the side edges 26 a toward the front side.
  • this stress causes the second raised portions 26 , like first raised portions 25 , to bulge toward the front side in an arched shape, and restricts the second raised portions 26 from being displaced as if pulled toward the rear side (displaced outward in the X-axis direction).
  • the side edges 26 a are restricted from being displaced in a direction away from the joints J.
  • the joints J between the first raised portions 25 and the second raised portions 26 are prevented from having clearances, and thus dark regions are prevented from being generated locally near the joints J (i.e., uneven brightness is prevented).
  • the two-dot chain lines therein respectively indicate the first raised portions 25 and the second raised portions 26 prior to the bulging.
  • the facing portions 28 are provided to both of the side edges 25 a of the pair of first raised portions 25 , and thus respectively positioned to correspond to the joints J at the four corners of the first reflection sheet 22 ( FIG. 3 ). As depicted in FIG. 9 , the facing portions 28 are formed to cover the entire length of the side edges 25 a of the first raised portions 25 . In addition, the facing portions 28 are superposed over and remain abutted on the side edges 26 a of the second raised portions 26 in the Y-axis direction to cover substantially the entire length thereof. With this arrangement, the second raised portions 26 are, substantially in their entire length, applied with the stress from the facing portions 28 , and thus the side edges 26 a of the second raised portions 26 are more reliably restricted from being displaced in the direction away from the joints J.
  • the first reflection sheet 22 is structured as follows.
  • the first raised portions (including the facing portions 28 ) have linear creases 29 extending in the X-axis direction at their raised base end positions (i.e., the boundary positions between the bottom 24 and the first raised portions 25 ).
  • Boundary portions BP 1 between the bottom 24 and the first raised portions 25 are bendable, as depicted in FIG. 11 .
  • such creases are not provided at the raised distal end positions of the first raised portions 25 (including the facing portions 28 ), i.e., at the boundary positions between the first raised portions 25 and the extensions 27 .
  • Boundary portions BP 2 between the first raised portions 25 and the extensions 27 are curved.
  • the boundaries between the bottom 24 and the first raised portions 25 are provided with perforations 30 adapted to facilitate the forming of the creases 29 , while such perforations are not provided at the boundaries between the first raised portions 25 and the extensions 27 .
  • the creases 29 are formed along the perforations 30 .
  • the first raised portions 25 and the extensions 27 are, while substantially collinear with each other, inclined with respect to the bottom 24 .
  • the first raised portions 25 are applied with stress that biases the first raised portions 25 to bulge toward the front side. Therefore, with no crease at the boundary between the first raised portions 25 and the extensions 27 , the first raised portions 25 are curved to bulge toward the front side (see, FIG. 11 ).
  • the boundary portions BP 1 between the bottom 24 and the first raised portions 25 are configured to be bent with the creases 29 , the influence exerted by the stress applied to the extensions 27 hardly reaches the bottom 24 .
  • the bottom 24 maintains its flat shape conforming to the bottom plate 14 a.
  • the above-described plurality of perforations 30 is configured to penetrate the first reflection sheet 22 , and juxtaposed linearly at intervals along the bend lines at the boundary positions.
  • the creases 27 are easily formed by bending the first raised portions 25 without decoupling the first raised portions 25 from the bottom 24 , and thus the first raised portions 25 are easily desirably bent with respect to the bottom 24 .
  • the second raised portions 26 have creases 31 respectively at their raised base end position and raised distal end positions (i.e., the boundary positions between the bottom 24 and the second raised portions 26 , and the boundary positions between the second raised portions 26 and the extensions 27 , respectively).
  • Boundary portions BP 3 and BP 4 respectively between the bottom 24 and the second raised portions 26 and between the second raised portions 26 and the extensions 27 , are bendable.
  • the boundaries between the bottom 24 and the second raised portions 26 and the boundaries between the second raised portions 26 and the extensions 27 are provided with perforations 32 similar to those provided to the above-described first raised portions 25 (see, FIG. 15 ).
  • the second raised portions 26 may be inclined with respect to the bottom 24 and the extensions 27 respectively at stabilized inclination angles (i.e., the configuration of the second raised portions will be stabilized.) as depicted in FIG. 19 .
  • the facing portions 28 of the side edges 25 a of the first raised portions 25 are easily positioned with respect to the side edges 26 a of the second raised portions 26 .
  • the facing portions 28 and the side edges 26 a are more reliably positioned to face each other.
  • the facing portions 28 extend relative to frontward inner surfaces (surface at the light exiting side) of the second raised portions 26 outward in the X-axis direction (i.e., the direction in which the second raised portions 26 are raised from the bottom 24 ) as depicted in FIG. 17 .
  • Extended distal end surfaces of the facing portions 28 are substantially in plane with rearward outer surfaces (surfaces at the side opposite to the light exiting side) of the second raised portions 26 .
  • the second raised portions 26 are displaced inward in the X-axis direction as in FIGS. 10 and 12 . Therefore, the extended distal ends of the facing portions 28 relatively protrude from the outer surfaces of the second raised portions 26 outward in the X-axis direction.
  • This exemplary embodiment is configured as above, and now operations thereof will be described. Initially, a method of manufacturing the first reflection sheet 22 will be described. By punching a large-sized base material for providing the first reflection sheet 22 with molds conformed to the spread shape of the first reflection sheet 22 , the first reflection sheet 22 spread as in FIG. 13 is obtained. At this time, the perforations 30 and 32 are formed at the bend positions of the spread first reflection sheet 22 . As depicted in FIGS.
  • the perforations 30 and 32 are provided respectively at the boundaries between the bottom 24 and the first raised portions 25 , the boundaries between the bottom 24 and the second raised portions 26 and the boundaries between the second raised portions 26 and the extensions 27 (i.e., bend positions), but no perforation is provided at the boundaries between the first raised portions 25 and the extensions 27 because these boundaries are not subjected to bending. Subsequently, the portions of the spread first reflection sheet 22 are bent at the bend positions along the perforations 30 and 32 .
  • the first reflection sheet 22 is valley-folded at the boundaries respectively between the raised portions 25 and 26 and the bottom 24 (the raised base end positions), while the first reflection sheet 22 is mountain-folded at the boundaries between the second raised portions 26 and the extensions 27 (the raised distal end positions).
  • the side edges 25 a of the first raised portions 25 and the side edges 26 a of the second raised portions 26 are abutted on each other to provide the joints J, and the inner surfaces of the facing portions 28 are abutted on the end surface of the side edges 26 a of the second raised portions 26 (see, FIGS. 16 and 17 ).
  • the facing portions 28 are easily and precisely abutted on the side edges 26 a because the configuration of the second raised portions 26 remains stabilized due to the creases 31 made along the perforations 32 at the boundaries respectively between the second raised portions 26 and the bottom 24 and between the second raised portions 26 and the extensions 27 (see, FIG. 19 ). Therefore, excellent operational reliability and efficiency are obtainable.
  • the facing portions 28 remain superposed over and abutted the second raised portions 26 , covering the entire length of second raised portions 26 in respect of the Y-axis direction (see, FIGS. 16 and 17 ).
  • no crease is provided between the extensions 27 continued from the raised distal ends of the first raised portions 25 and the raised portions 25 , and the extensions 27 are substantially collinear with the first raised portions (see, FIG. 18 ).
  • the first reflection sheet 22 bent as described above is housed for use in the backlight unit 12 assembled in the following process.
  • the LED boards 18 having the preliminary assembled LEDs 17 , the diffusing lenses 19 and the second reflection sheet 23 are housed in the chassis 14 , and then the first reflection sheet 22 is laid in the chassis 14 .
  • the holding members 20 and the optical member 15 are, in this order, mounted thereto.
  • the diffusing lenses 19 are inserted into the corresponding lens insertion holes 22 a of the bottom 24 , and the insertion holes 22 b are communicated with the insertion holes 23 c of the second reflection sheet 23 .
  • the insertion holes 22 b are communicated with the insertion holes 23 c of the second reflection sheet 23 .
  • the extensions 27 continued from the second raised portions 26 are mounted on the receiving plate 14 d to extend in parallel thereon substantially without any clearances therebetween.
  • the extensions 27 continued from the first raised portions 25 are collinear with the first raised portions 25 to rise up above the receiving plate 14 d (be spaced apart from the receiving plate 14 d ), thereby inclining with respect to the receiving plate 14 d .
  • the distance between the extensions 27 continued from the first raised portions 25 and the receiving plate 14 d is increased as from extending base ends of the extensions 27 (ends closer to the first raised portions 25 ) toward extending distal ends of the extensions 27 , and in other words, the further the extensions 27 extend away from the first raised portions 25 , the greater the distance becomes.
  • the raised portions 25 and 26 , the lateral plate 14 c and the bottom plate 14 a define the substantially triangular space S in a side view.
  • the diffuser plate 15 a and the optical sheets 15 b are, in this order, mounted on the receiving plate 14 d .
  • the extensions 27 are to be sandwiched between the diffuser plate 15 a and the receiving plate 14 d .
  • the extensions 27 continued from the first raised portions 25 , which rise up above the receiving plate 14 d before the diffuser plate 15 a is mounted (see, FIG. 18 ), are pressed toward the rear side by the diffuser plate 15 a and deformed to extend parallel to the receiving plate 14 d .
  • the extensions 27 are displaced toward the rear side more greatly at the extending distal end side than at the extending base end side, in accordance with the distance by which the extensions 27 are spaced apart from the receiving plate 14 d .
  • the first raised portions 25 are applied from the extension 27 with the stress that biases the first raised portions 25 toward the front side.
  • the first raised portions 25 are deformed to bulge toward the front side, thereby forming an arched shape.
  • the boundary portions BP 2 between the first raised portions 25 and the extensions 27 are curved without forming a crease.
  • the facing portions 28 provided to the side edges 25 a thereof are likewise deformed to bulge toward the front side, thereby forming an arched shape.
  • the second raised portions 26 which face the facing portions 28 , are applied from the facing portions 28 with the stress that biases the second raised portions 26 toward the front side.
  • the second raised portions 26 may also be deformed to bulge toward the front side and form an arched shape similarly to the first raised portions 25 , as depicted in FIGS. 10 and 12 .
  • the second raised portions 26 depending on the strength of the stress applied, may not be deformed to bulge in an arched shape.
  • the second raised portions 26 do receive the stress that biases the second raised portions 26 toward the front side.
  • the first and second raised portions 25 and 26 are restricted from displacing toward the rear side, i.e., in the direction opposite to the light exiting side.
  • the backlight unit 12 manufactured as described above is assembled to the separately-manufactured liquid crystal panel 11 and integrated together by the bezel 13 , whereby the liquid crystal display device 10 is manufactured.
  • the LEDs 17 included in the backlight unit 12 are lighted up, and image signals are fed to the liquid crystal panel 11 .
  • a predetermined image is displayed on a display of the liquid crystal panel 11 .
  • the light emitted by the lighted LEDs 17 is initially incident on the light incident surfaces 19 a of the diffusing lenses 19 , as depicted in FIGS. 7 and 8 .
  • the majority of the light is incident on the tilted surfaces of the light-incident recesses 19 c provided to the light incident surfaces 19 a .
  • the tilted surfaces then refract the light at a wide angle according to their tilted angles, and the light is incident into the diffusing lenses 19 .
  • the incident light after traveling through the diffusing lenses 19 , exits from the light exiting surfaces 19 b .
  • the light exiting surfaces 19 b which are substantially flatly spherical, let out the light while refracting the light at a wider angle by their interfaces with an outer air layer.
  • the light-exiting surfaces 19 b serve to let out the light by refracting the light at a wide angle with the circumferential surfaces of the light exiting recesses 19 e , or serve to reflect the light to the LED boards 18 .
  • the light returned to the LED boards 18 is reflected by the second reflection sheet 23 to the diffusing lenses 19 , and is incident again on the diffusing lenses 19 . Since the light is efficiently utilized, high brightness is obtainable.
  • the diffusing lenses 19 are adapted to diffuse highly directional light emitted by the LEDs 17 at a wide angle.
  • the light incident on the optical member 15 may be distributed uniformly in the plane of the optical member 15 .
  • the regions between the adjacent LEDs 17 are less visibly recognized as dark regions, which enables the distances between the LEDs 17 to be increased.
  • the number of LEDs 17 is reducible while restricting uneven brightness. Since the distances between the adjacent LEDs 17 are increased by reducing the number of the LEDs 17 , the holding members 20 are mountable with use of the saved regions. Thus, the holding members 20 strengthen the fixing of the LED boards 18 .
  • the bottom 24 is expanded in the long-side direction (the X-axis direction) in a greater amount than in the short-side direction (the Y-axis direction).
  • the short sides of the bottom 24 i.e., the raised base end positions of the second raised portions 26
  • the raised distal end positions of the second raised portions 26 are substantially fixed, with the extensions 27 continued therefrom sandwiched between the receiving plate 14 d and the diffuser plate 15 a .
  • the raised base end positions of the second raised portions 26 will come closer to the raised distal end positions thereof, thereby reducing the distance therebetween and generating a deflection of the second raised portions 26 .
  • the second raised portions 26 can be displaced as if pulled toward the rear side, and deformed.
  • the second raised portions 26 are applied from the facing portions 28 the stress that biases the second raised portions 26 toward the front side.
  • the second raised portions 26 are restricted from being displaced as if pulled toward the rear side.
  • the joints J between the first raised portions 25 and the second raised portions 26 are prevented from having clearances.
  • the two-dot chain lines therein indicate the second raised portions 26 before thermally expanded.
  • the second raised portions 26 are deformed to bulge in an arched shape (i.e., curved opposite to the direction of the concerned deflective deformation), thereby generating a tension between the raised base ends and the raised distal ends, the second raised portions 26 are more reliably prevented from being displaced as if pulled toward the rear side. Furthermore, the facing portions 28 , which are provided to cover the entire length of the side edges 25 a of the first raised portions 25 , are abutted on the side edges 26 a of the second raised portions 26 while covering the entire length of the side edges 26 a . Accordingly, the second raised portions 26 are applied with the above stress in its entire length.
  • the joints J between the first raised portions 25 and the second raised portions 26 are prevented from having clearances. Therefore, the light within the internal space defined by the first reflection sheet 22 in the backlight unit 12 is prevented from leaking to the outside through the vicinity of the joints J. Accordingly, the light exiting surface of the entire backlight unit 12 is prevented from generating dark regions locally at the four corners thereof where the joints J are positioned, and thus uniform brightness is achieved in an entire plane surface of the light exiting surface. Since the light exited from the backlight unit 12 is configured to be uniform without unevenness, the display of the liquid crystal display device 10 exhibits good display quality.
  • the backlight unit 12 includes: the LEDs 17 serving as a light source; the chassis 14 including the bottom plate 14 a located opposite to the light exiting side relative to the LEDs 17 , the chassis housing the LEDs 17 ; and the first reflection sheet 22 adapted to reflect light, the first reflection sheet 22 including the quadrangular bottom 24 extending along the bottom plate 14 a , and at least two raised portions 25 and 26 respectively raised from at least adjacent two sides of the bottom 24 toward the light exiting side, the joints J being provided between the adjacent two side edges 25 a and 26 b of the raised portions 25 and 26 .
  • the side edge 25 a of the first raised portion 25 of the at least two raised portions 25 and 26 includes the facing portion 28 that faces the side edge 26 a of the second raised portion 26 in a direction where the first raised portion 25 is raised from the bottom 24 (outward in the Y-axis direction), and the first raised portion 25 and the facing portion 28 bulge toward the light exiting side.
  • the light from the LEDs 17 is reflected by the first reflection sheet 22 having the bottom 24 and the raised portions 25 and 26 , and the light is efficiently let out.
  • the joints J are provided in the first reflection sheet 22 . If the second raised portion 26 should be deformed to be displaced opposite to the light exiting side, clearances may be brought to the joints J. Accordingly, the light may leak out through the clearances, thus dark regions may be locally generated.
  • One of the solutions to such problem is, for instance, to increase the number of LEDs 17 in the vicinity of the joints J. However, the increase in the number of LEDs 17 will lead to a cost increase.
  • the side edges 25 a of the first raised portion 25 of the at least two raised portions 25 and 26 is provided with the facing portion 28 that faces the side edge 26 a of the second raised portion 26 in the direction where the first raised portion 25 is raised from the bottom 24 (outward in the Y-axis direction), and further, the first raised portion 25 and the facing portion 28 bulge toward the light exiting side. Accordingly, the side edge 26 a of the second raised portion 26 is applied from the facing portion 28 opposed thereto the stress that biases the second raised portion 26 toward the light exiting side.
  • the stress applied from the facing portion 28 restricts the second raised portion 26 from being displaced in a direction opposite to the light exiting side, and the second raised portion 26 becomes more invulnerable to deflective deformation.
  • the joints J between the side edge 25 a of the first raised portion 25 and the side edge 26 a of the second raised portion 26 are prevented from having clearances. Therefore, without increasing the number of LEDs 17 , the light is prevented from leaking out through the joints J, and uneven brightness is restricted at low cost.
  • the bottom 24 is elongated quadrangular, and the second raised portions 26 are raised from the short sides of the bottom 24 while the first raised portions 25 having the facing portions 28 are raised from the long sides of the bottom 24 .
  • the bottom 24 tends to be thermally expanded in the long-side direction in a greater amount than in the short-side direction.
  • the raised base end positions of the second raised portions 26 raised from the short sides are displaced in accordance with the thermal expansion of the bottom 24 in the long-side direction, and the second raised portions 26 are easily deformed.
  • the first raised portions 25 raised from the long sides are provided with the facing portions 28 .
  • the facing portions 28 serve to restrict the second raised portions 26 at the short sides from being displaced in the direction opposite to the light exiting side. Therefore, the joints J are prevented from having clearances, and thus the light is favorably prevented from leaking out therethrough.
  • the second raised portions 26 are raised from the paired short sides of the bottom 24 while the first raised portions 25 are raised from the paired long sides of the bottom 24 . Both of the side edges 25 a of the paired first raised portions 25 are provided with the facing portions 28 . According to this arrangement, since the facing portions 28 are provided to both of the side edges 25 a of the first raised portions 25 raised from the long sides adjacent to the short sides, both of the side edges 26 a of the paired second raised portions 26 raised from the short sides are applied with the stress from the facing portions 28 . Thus, the second raised portions 26 are more reliably restricted from being displaced in the direction opposite to the light exiting side. With this arrangement, the four joints J provided between the side edges 26 a and 25 a respectively of the adjacent paired second raised portions 26 and paired first raised portions 25 are prevented from having clearances, and thus uneven brightness is effectively restricted.
  • the angles at which the paired second raised portions 26 are raised from the bottom 24 are substantially equal, and the angles at which the paired first raised portions 25 are raised from the bottom 24 are substantially equal.
  • the light will be reflected by the paired second raised portions 26 each substantially at an equal angle.
  • the light will be reflected by the paired first raised portions 25 each substantially at an equal angle. Accordingly, the reflection light reflected by the first reflection sheet 22 may exhibit less unevenness, and thus uneven brightness further restricted.
  • the diffuser plate 15 a is provided as the optical member 15 positioned at the light exiting side with respect to the LEDs 17 . While at least the raised distal ends of the first raised portions 25 are provided with the extensions 27 extending outwardly, the chassis 14 is provided with the receiving plate 14 d adapted to sandwich with the diffuser plate 15 a the extensions 27 . According to this arrangement, for example, when the diffuser plate 15 a is mounted to the receiving plate 14 d while the extensions 27 are raised above the receiving plate 14 d , the first raised portions 25 are applied with the stress that biases the first raised portions 25 toward the light exiting side in accordance with the sandwiching of the extensions 27 therebetween.
  • the first raised portions 25 together with the facing portions 28 , bulge toward the light exiting side, and the facing portions 28 apply to the second raised portions 26 the stress that biases the side edges 26 a of the second raised portions 26 toward the light exiting side.
  • the second raised portions 26 also budge toward the light exiting side, together with the first raised portions 25 and the facing portions 28 .
  • the second raised portions 26 bulge toward the light exiting side with the stress from the facing portions 28 , the second raised portions 26 are more reliably restricted from being displaced in the direction opposite to the light exiting side. Accordingly, the joints J do not easily have clearances, and thus the leaking out of the light is favorably prevented.
  • the boundary portions BP 1 between the bottom 24 and the first raised portions 25 are bent at the creases 29 while the boundary portions BP 2 between the first raised portions 25 and the extensions 27 are curved with no crease.
  • the arrangement where the boundary portions BP 2 between the first raised portions 25 and the extensions 27 are curved with no crease will relatively increase the stress applied to the first raised portions 25 when the extensions 27 are sandwiched between the diffuser plate 15 a and the receiving plate 14 d , as compared to an arrangement where the boundary portions BP 2 are bent at creases.
  • the stress applied from the facing portions 28 to the side edges 26 a of the second raised portions 26 is increased, and therefore the second raised portions 26 is more reliably restricted from being displaced in the direction opposite to the light exiting side. Accordingly, the joints J do not easily have clearances, and thus the leaking out of the light is favorably prevented.
  • the boundaries between the bottom 24 and the first raised portions 25 and the boundaries between the first raised portions 25 and the extensions 27 are provided with the perforations 30 that serve as recesses for facilitating the forming of the creases 29 .
  • the perforations 30 facilitate the forming of the creases 29 at the boundaries.
  • the first raised portions 25 are easily formed into a desirable configuration.
  • the boundaries between the first raised portions 25 and the extensions 27 are provided with no perforations, and thus creases are hardly made. Therefore, the stress is more reliably applied to the first raised portions 25 when the extensions 27 are sandwiched between the diffuser plate 15 a and the receiving plate 14 d.
  • the raised distal ends of the second raised portions 26 are provided with the extensions 27 extending outward.
  • the boundaries between the bottom 24 and the second raised portions 26 and the boundaries between the second raised portions 26 and the extensions 27 are provided with the perforations 32 that serve as recesses for facilitating the forming of the creases 31 .
  • the perforations 32 facilitate the forming of the creases 31 at the boundaries.
  • the configuration of the second raised portions 26 is stabilized.
  • the facing portions 28 of the first raised portions 25 are easily and reliably placed to face the side edges 26 a of the second raised portions 26 , thereby more reliably applying the stress from the facing portions 28 to the second raised portions 26 .
  • the recesses include the plurality of perforations 30 and 32 juxtaposed linearly at intervals. With this arrangement, the recesses (perforations 30 and 32 ) are formed at low cost at the time of manufacturing the first reflection sheet 22 .
  • the facing portions 28 are provided to the side edges 25 a of the first raised portions 25 to cover the entire length thereof. According to this arrangement, the facing portions 28 provided to the side edges 25 a of the first raised portions 25 to cover the entire length thereof may apply the stress to the second raised portions 26 , and thus more reliably restrict the second raised portions 26 from being displaced in the direction opposite to the light exiting side. Therefore, the joints J are more steadily prevented from having clearances.
  • the raised portions 25 and 26 are inclined with respect to the bottom 24 . Accordingly, the raised portions 25 and 26 serve to reflect the light toward the light exiting side at a favorable angle.
  • the raised portions 25 and 26 are substantially linear. Thus, the raised portions 25 and 26 serve to reflect the light toward the light exiting side at a more favorable angle.
  • the chassis 14 includes the lateral plate 14 c that stands from the bottom plate 14 a and defines with the raised portions 25 and 26 the space S. Since the space S is maintained between the second raised portions 26 and the lateral plate 14 c , the second raised portions 26 may be adversely deformed to recede into the space S. However, the facing portions 28 provided to the side edges 25 a of the first raised portions 25 favorably restrict the above displacement of the second raised portions 26 , and thus the light is prevented from leaking through the joints J.
  • the light source may be LEDs 17 .
  • LEDs 17 may be LEDs 17 .
  • the plurality of LEDs 17 is mounted on the LED boards 18 that extend parallel to the bottom plate 14 a and the bottom 24 .
  • the LEDs 17 need to be arranged on the LED boards 18 in a disproportional manner.
  • manufacturing of dedicated LED boards will be required, which leads to a cost increase.
  • the facing portions 28 are provided to the side edges 25 a of the first raised portions 25 of the first reflection sheet 22 as described above, which serves to dispense with a known method.
  • general-purpose LED boards 18 on which the LEDs 17 are regularly disposed are usable. Accordingly, further a cost reduction is achievable.
  • the diffusing lenses 19 which are adapted to diffuse the light from the LEDs 17 and let out the light, are positioned at the light exiting side relative to the LEDs 17 . With this arrangement, the light emitted by the LEDs 17 is diffused by the diffusing lenses 19 and let out through the diffusing lenses 19 . Accordingly, since the let-out light exhibits less unevenness, the number of the LEDs 17 is reducible, and thus a cost reduction is achievable.
  • a second exemplary embodiment according to an aspect of the present invention will be described with reference to FIGS. 21 to 25 .
  • the light source in the above first exemplary embodiment is replaced by a hot cathode tube 40 , and a diffuser plate 115 a has a different configuration.
  • the configurations, operations and effects similar to those of the above first exemplary embodiment will not be described in duplicate.
  • the backlight unit 112 uses the hot cathode tube 40 as its light source.
  • the hot cathode tube 40 which is in its entirety tubular (linear), includes a hollow glass tube and a pair of electrodes provided at both ends of the glass tube.
  • the glass tube is encapsulated with mercury and noble gas, and its inner wall surface is applied with a fluorescent material.
  • the hot cathode tube 40 which has its emitting surface on an outer circumference of the glass tube, is adapted to emit light radially from its axial core. Both ends of the hot cathode tube 40 are fitted into sockets (not illustrated). Via the sockets, the electrodes are connected to a power supply board attached to an outer surface (rear surface) of a bottom plate 114 a of a chassis 114 , and fed with power supply therefrom.
  • the hot cathode tube 40 configured as above is singularly housed in the chassis 114 with its long-side direction (axial direction) coincident with a long-side direction of the chassis 114 .
  • the hot cathode tube 40 is positioned substantially at the middle of the chassis 114 in a short-side direction of the chassis 114 .
  • the hot cathode tube 40 is positioned at the center portion 114 C, thereby providing a light-source arranged region LA.
  • the first end portion 114 A and the second end portion 114 B of the chassis 114 at neither of which the hot cathode tube 40 is positioned, provide no-light-source arranged regions LN.
  • the hot cathode tube 40 is arranged locally at the center portion 114 C (i.e., middle position of the bottom plate 114 a of the chassis 114 in the short-side direction) to provide the light-source arranged region LA.
  • the area of the light-source arranged region LA (longitudinal dimension in the Y-axis direction) is smaller than the area of the no-light-source arranged regions LN (longitudinal directions in the Y-axis direction).
  • the proportion of the area of the light-source arranged region LA (longitudinal dimension in the Y-axis direction) to the area of the entire screen (vertical dimension (short-side dimension) of the screen) is exemplarily set to be approximately 4%.
  • the areas of the paired non-light-source arranged regions LN are substantially equal.
  • the second reflection sheet 23 used in the above-described first exemplary embodiment is dispensed, and only the first reflection sheet 22 used in the first exemplary embodiment is used as a reflection sheet 121 .
  • the reflection sheet 121 is configured similarly to the first reflection sheet 22 described in the first exemplary embodiment, and has the facing portions 28 as well (see, FIG. 21 ).
  • the diffuser plate 115 a includes a base substrate in the entire of which light transmittance and light reflectance are substantially uniform with diffusing particles blended therein in a dispersed manner.
  • the base substrate of the diffuser plate 115 a is preferably configured to exhibit, for instance, the light transmittance of approximately 70% and the light reflectance of approximately 30%.
  • the diffuser plate 115 a has a rear surface opposed to the hot cathode tube 40 (hereinafter referred to as first surface 115 a 1 ) and a front surface located opposite to the first surface 115 a 1 and opposed to the liquid crystal panel 11 (hereinafter referred to as second surface 115 a 2 ).
  • the first surface 115 a 1 serves as a light incident surface through which the light from the hot cathode tube 40 is incident
  • the second surface 115 a 2 serves as a light exiting surface through which the light (illumination light) is let out toward the liquid crystal panel 11 .
  • a dot-patterned light reflector 41 of white color is provided on the first surface 115 a 1 of the diffuser plate 115 a (i.e., the light incident surface).
  • the light reflector 41 is configured such that a plurality of dots 41 a circular in a planar view are disposed in a zigzag manner (staggered or alternate manner).
  • the dot pattern of the light reflector 41 is formed by printing, for instance, paste containing metal oxide onto the surface of the diffuser plate 115 a .
  • the printing is preferably screen printing, ink jet printing or the like.
  • the light reflector 41 is configured to exhibit by itself, for example, the light reflectance of approximately 75%.
  • the light reflector has a greater light reflectance.
  • the light reflectance of each material is an average light reflectance exhibited within a diameter of an area measured by CM-3700d LAV (measurement diameter of 25.4 mm) manufactured by Konica Minolta Optics, Inc.
  • the light reflectance of the light reflector 41 itself is measured such that: the light reflector 41 is formed to cover the entire surface of the glass substrate; and the surface on which the light reflector 41 is formed is measured by the above measurement method.
  • the diffuser plate 115 a which extends in a long-side direction (the X-axis direction) and a short-side direction (the Y-axis direction), changes the light reflectance of the first surface 115 a 1 (i.e., the surface of the diffuser plate 115 a opposed to the hot cathode tube 40 ) along the short-side direction as depicted in FIG. 25 , by changing the dot pattern of the first reflector 41 (see, FIG. 23 ). In other words, as depicted in FIG.
  • the diffuser plate 115 a is configured such that, in the entirety of the first surface 115 a 1 , a section superposed over the hot cathode tube 40 (hereinafter referred to as light-source superposed section DA) exhibits a greater light reflectance than sections not superposed over the hot cathode tube 40 (hereinafter referred to as no-light-source superposed section DN).
  • the light reflectance exhibited by the first surface 115 a 1 of the diffuser plate 115 a is substantially constant in the long-side direction with little changes (see, FIG. 23 ).
  • a light reflectance distribution in the diffuser plate 115 a will be described in detail. As depicted in FIGS. 23 to 25 , the light reflectance of the diffuser plate 115 a is sequentially reduced as away from the hot cathode tube 40 in the short-side direction (the Y-axis direction), and sequentially increased as close to the hot cathode tube 40 in the short-side direction (the Y-axis direction).
  • a distribution of the light reflectance is adapted to be a normal distribution (the distribution describes a bell-shaped curved line).
  • the light reflectance of the diffuser plate 115 a is maximized at the middle position of the diffuser plate 115 a in the short-side direction (position coincident with the center of the hot cathode tube 40 ) and minimized at both ends of the diffuser plate 115 a in the short-side direction.
  • the maximum of the light reflectance is exemplarily set at approximately 65%
  • the minimum of the light reflectance is exemplarily set at approximately 30% (i.e., equal to the light reflectance of the diffuser plate 115 a itself). Accordingly, at both ends of the diffuser plate 115 a in the short-side direction, the light reflector 41 is disposed only in a small amount or the light reflector 41 is hardly disposed.
  • the light reflector 41 is configured as follows. Out of the dots 41 a included in the light reflector 41 , the dots 41 a located at the middle position of the diffuser plate 115 a in the short-side direction (i.e., the dots 41 a positioned to correspond to the center position of the hot cathode tube 40 ) have the maximum areas. The areas of the dots 41 a are gradually reduced as the dots 41 a are located away from the middle position of the diffuser plate 115 a in the short-side direction, and the dots 41 a located at the positions closest to the ends of the diffuser plate 115 a in the short-side direction have the minimum areas.
  • the above-configured diffuser plate 115 a serves to moderate the brightness distribution of the illumination light, which consequently leads to the moderated illumination brightness distribution of the backlight unit 112 as a whole.
  • the light reflectance may be adjusted by changing the distances between the dots 41 a of the light reflector 41 while equalizing the areas of the dots 41 a.
  • the hot cathode tube 17 is switched on as depicted FIG. 23 , the light incident efficiency is properly controlled per each region of the diffuser plate 115 because the first surface 115 a 1 of the diffuser plate 115 through which the light emitted therefrom is incident is provided with the light reflector 41 that exhibits different light reflectance depending on its in-plane region.
  • the light-source superposed section DA of the first surface 115 a 1 superposed over the hot cathode tube 40 is exposed to direct light from the hot cathode tube 40 in a relatively greater amount than the no-light-source superposed sections DN of the first surface 115 a 1 . Accordingly, by relatively increasing the light reflectance (the areas of the dots 41 a ) of the light reflector 41 at the light-source superposed section DA (see, FIGS. 23 and 25 ), the light incident on the first surface 115 a 1 is suppressed (restricted) and much of the light is reflected to return to the chassis 114 .
  • the no-light-source superposed sections DN of the first surface 115 a 1 not superposed over the hot cathode tube 40 are exposed to direct light from the hot cathode tube 40 in a relatively smaller amount than the light-source superposed sections DA of the first surface 115 a 1 . Therefore, by relatively reducing the light reflectance (the areas of the dots 41 a ) of the light reflector 41 at the no-light-source superposed sections DN (see, FIGS. 23 and 25 ), the light is facilitated to be incident on the first surface 115 a 1 .
  • the no-light-source superposed sections DN are compensated with the light by guiding to the no-light-source superposed sections DN with use of the reflection sheet 121 the light reflected to the chassis 114 by the light reflector 41 of the light-source superposed section DA, and thus the sufficient amount of the light is reliably incident on the no-light-source superposed sections DN.
  • the light emitted by the hot cathode tube 40 is subjected to the above-described optical effects while being transmitted through the diffuser plate 115 a , and converted within the plane of the diffuser plate 115 a into substantially uniform planar light having no unevenness. Then, the light is subjected to further optical effects through the optical sheets 15 b and illuminated onto the liquid crystal panel 11 .
  • the backlight unit 112 includes the diffuser plate 115 a (i.e., the optical member 115 ) located at the light exiting side relative to the hot cathode tube 40 (i.e., the light source).
  • the portion of the chassis 114 opposed to the diffuser plate 115 a is divided into the light-source arranged region LA arranged with the hot cathode tube 40 and the no-light-source arranged regions LN not arranged with the hot cathode tube 40 .
  • the light emitted by the hot cathode tube 40 is initially incident on the portion of the diffuser plate 115 a having a relatively great light reflectance (the light-source superposed section DA), and much of the light is reflected (in other words, is not transmitted through the diffuser plate 115 a ).
  • the brightness of the illumination light is restricted irrespective of the amount of the light emitted by the hot cathode tube 40 .
  • the light reflected by the light-source superposed section DA is adapted to be re-reflected by the reflection sheet 121 in the chassis 114 to be directed to the no-light-source arranged regions LN.
  • the portion superposed over the no-light-source arranged regions LN (the no-light-source superposed sections DN) exhibits a relatively small light reflectance, and much of the light is transmitted therethrough.
  • the illumination light is adapted to achieve the predetermined brightness.
  • the portion of the chassis 114 opposed to the diffuser plate 115 a is divided into the first end portion 114 A, the second end portion 114 B positioned at the end of the chassis 114 opposite to the first end portion 114 A and the center portion 114 C interposed between the first end portion 114 A and the second end portion 114 B, and the center portion 114 C serves as the light-source arranged region LA while the first and second end portions 114 A and 114 B serve as the no-light-source arranged regions LN.
  • sufficient brightness is reliably attained at the center of the backlight unit 112 , and thus a liquid crystal display device 110 including the backlight unit 112 also reliably obtains the brightness at its display center. Therefore, good visibility is obtainable.
  • the light source is provided by the hot cathode tube 40 . Accordingly, the enhancement of the brightness and the like are realized.
  • a third exemplary embodiment according to an aspect of the present invention will be described with reference to FIG. 26 .
  • the light source in the above second exemplary embodiment is replaced by a cold cathode tube 50 .
  • the configurations, operations and effects similar to those of the above first exemplary embodiment will not be described in duplicate.
  • the cold cathode tube 50 which serves as the light source according to this exemplary embodiment, is shaped like an elongated tube (linear shape).
  • the cold cathode tube 50 includes an elongated hollow glass tube with both ends thereof sealed, and a pair of electrodes encapsulated into both ends of the glass tube.
  • the glass tube is encapsulated with mercury and noble gas, and its inner wall surface is applied with a fluorescent material.
  • Both ends of the cold cathode tube 50 are provided with relay connectors (not depicted), and lead terminals protruding from the electrodes to the outside of the glass tube are connected to the relay connectors.
  • the cold cathode tube 50 is connected to an inverter board (not depicted) attached to an outer surface of a bottom plate 214 a of a chassis 214 , and controllably driven.
  • the cold cathode tube 50 has an smaller outer diameter than the hot cathode tube 40 of the above second exemplary embodiment (which exemplarily has an outer diameter of approximately 15.5 mm), and the outer diameter of the cold cathode tube 50 is exemplarily set at approximately 4 mm.
  • the above-configured cold cathode tube 50 is arranged in the chassis 214 in a disproportional manner such that six cold cathode tubes 50 are juxtaposed in parallel to each other at predetermined intervals (alignment pitches) with their longitudinal direction (axial directions) coincident with the long-side direction of the chassis 124 .
  • the cold cathode tube 50 is positioned at the center portion 214 C of the bottom plate 214 a , thereby providing a light-source arranged region LA.
  • the light-source arranged region LA according to this exemplary embodiment is larger than the light-source arranged region LA according to second exemplary embodiment.
  • a reflection sheet 221 which is configured similarly to the reflection sheet 121 of the above second exemplary embodiment, includes the facing portions 28 .
  • the light source is provided by the cold cathode tube 50 .
  • the present invention is not limited to the above exemplary embodiments explained in the above description.
  • the following exemplary embodiments may be included in the technical scope of the present invention, for example.

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  • Mathematical Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Planar Illumination Modules (AREA)
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JPWO2011074366A1 (ja) 2013-04-25
RU2516380C2 (ru) 2014-05-20
EP2515028A1 (en) 2012-10-24
EP2515028B1 (en) 2017-05-03
BR112012015874A2 (pt) 2019-09-24
CN102667310B (zh) 2014-12-03
RU2012124902A (ru) 2014-01-27
JP5355714B2 (ja) 2013-11-27

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